System of electrical distribution for projector arc-lighting.



J. H. HALLBERG.

SYSTEM OF ELECTRICAL DISTRIBUTION FOR PROJECTOR ARC LIGHTING.

APPLICATION FILED IULYIT. I915 1,184,745. Patented May 30,1916.

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SYSTEM 0F,ELECTRICAL DiSTRlBUTl'ON FOR PROJECTOR ARC LIGHTING.

APPLICATION FILED JULY 11, I915.

1,1 84,745 Patented May 30, 1916.

2 SHEETS-SHEET 2.

Wu neooao UNITED STATES PATENT OFFICE.

JOSEF HENRIK HALLBEIRG, OF NEW YORK, N. Y.

SYSTHI OF ELECTRICAL DISTRIBUTION FOR PROJECTOR ARC-LIGHTING.

Application filed July 17, 1915.

To all whom it may concern Be it known that I, J OSEF HENRIK HALL- BERG, a citizen of the United States, residing at New York city, in the county and State of New York, have invented certain new and useful Improvements in Systems of Electrical Distribution for Projector Arc- Lighting, of which the following is a specification.

My invention relates to a system of electrical distribution which is more especially adapted for the operation of projector arc lamps, such as required for the search lights on battleships, for stereopticons, etc.

One of the objects of this invention is to provide an operative system which does not require the usual large resistance in series with the arc of the projector, and therefore may be operated at a maximum efficiency, with a corresponding economy in the size of the generator and the other equipment required and in the cost of operation. This is especially important on battleships where the saving space and weight are most essential.

Another object of this invention is to provide a system in which a single generator may supply current to a single are or to a plurality of arcs alternately, the field magnet circuits being correspondingly changed from a differential winding causing a constant current output, to a compound winding producing a substantially constant potential output.

In the accompanying drawings, Figures 1 and 2 represent, diagrammatically, an arrangement of circuits for carrying out my invention, the field windings in Fig. 1 acting differentially, and the generator supplying current to a single arc, while in Fig. 2 the shunt and series windings assist to produce a compounded generator which supplies current to two arcs connected in parallel; Figs. 3 and 4 illustrate a modified arrangement of circuits for producing the same results.

The generator is of the direct current type, and is provided with series and shunt field windings 2 and 3 respectively, and an armature 4. The are lamp projectors 78 may be of any suitable construction and are provided, as usual, with means for throwing them into or out of operation.

The main leads 9-10, from the armature brushes 56, are connected to the plugs 1214 of the switchboard 15, the series Specification of Letters Patent.

Patented May 30, 1916.

Serial No. 40,436.

field coil 2, being connected to the plugs 1617 and the shunt coil 3 to the plug 18 and the brush 6.

For the purpose of reversing the connections of the series field coil 2 when it is desired to shift from one arc in circuit to two arcs, or vice versa, I provide a switch havlng insulated blades 20-21, pivoted at 232L. Cooperating with these blades are contacts 2525 connected by conductor 2 with one terminal of the series field coil 2 at plug 17 and 26, connected by conductor 2* with the other terminal of said series coil 2 at plug 16. lVhen the switch is in the position shown in Fig. 1, the series and shunt field coils act differentially, and when the switch is shifted to the position illustrated in Fig. 2, the coils assist and constitute a compound field winding.

One terminal of each are 78 is connect ed to the negative lead 10, and through it to brush 6, the other terminals being connected respectively to the contacts 2728, the contacts 2728 being connected by the twopart resistance coil 2929, the central point of which is connected by conductor 2 with the switch blade 21. An insulated plate 30, carried by the switch, short circuits the resistance coil 29*29 when in the position shown in Fig. 1. The switch blade 20 is connected by the conductor 9, with the positive brush 5, and by the conductor 3* with one terminal of the shunt coil 3.

13 is a resistance in conductor 3 which is short circuited when the handle of the switch is thrown to the left.

The operation of the system will be readily understood from the previous detailed description of the circuits. In Fig. 1, only the lamp 7 is in operation, the other lamp 8 being cut out so that no current flows through the conductor 8. Vith the switch in the position shown, the series coil 2 cpposes or bucks the shunt coil 3, the field produced therefore, being the resultant of the differential effect of the two coils.

The machine is wound to generate a voltage slightly greater than that required by the are when operating with a differential field winding. For instance, if the normal voltage required at the terminals of the arc is fifty volts, I wind the machine to produce about seventy volts when operating with shunt coil alone, the opposing effect of the series coil reducing the excitation so that the machine generates under normal conditions of the arc, a voltage substantially the same as that across the are, if the slight drop across the parallel connected resistance coils 29-29 is disregarded. Under these conditions, the varying resistance across the arc is the controlling factor of the system and the generator operates as a constant current machine, thereby eliminating the necessity for the use of the usual resistance unit in series with the arc, with the attendant consumption of energy. If, therefore, the carbons of the are should be brought together by accident or otherwise, as they are liable to be when subjected to the great vibrations produced during the firing of modern guns on battleships, no disastrous short circuit effect can be produced with the arrangement shown in Fig. 1, because the increased current through the series coil would instantly neutralize the field of the shunt coil, thereby practically reducing the voltage 'of the armature to zero. Accordingly, with my system as illustrated in Fig. 1, a short circuit of the carbons cannot produce any damaging effects or inconveniences, such as the blowing of fuses consequent upon an overload condition. 7

When it is desired to operate both are lamps, the handle 22 is thrown to the left, bringing the switch into the position shown in Fig. 2, and the lamp 8 is then cut into operation. The current being reversed through the series coil 2, the generator operates as a normally compounded machine and maintains a substantially constant potential across the parallel connected lamps. The resistance 13, in the shunt circuit is short circuited, thereby increasing the shunt field strength and placing the generator in a more favorable condition to maintain a constant potential output under increased load. At the same time, the parallel arrangement of the two-part resistance is changed and the parts 29-29 are inserted separately in series with the lamps. The facility with which this change can be made, from the arrangement in Fig. 1, adapted to operate a single lamp upon a constant current output, to that of Fig. 2, supplying current at constant potential to two lamps in parallel, makes this system especially advantageous for use in moving picture theaters, because, with a generator of a given size, it is possible to obtain the maximum ampere output with perfect regulation and with only a very small resistance in series withthe are when operating a single projector, and when near "the end of one picture film, the controlling switch may be thrown over, thereby slightly reducing the current of the running lamp and allowing the operator to start the second lamp so as to have a steady, perfectly centered light, ready to permit the second projectorto be cut in instantly and thus produce the pleasing dissolving effect on the screen. It will be observed, that when the switch is in the position shown in Fig. 1, the parts 29-29 are in parallel thereby placing only a very small resistance in series with the are 7, and that as the plate 30 leaves the clip 28, in being moved to the left, the parallel connection of the two-part resistance is broken and the part 29 alone is in circuit with the lamp 7 thus increasing the resistance effect two-fold. While the use of the series resistance is not essential, this effect of momentarily increasing the resistance by the slight manipulation of the switch is a convenience to the operator in case the arc is required to be extinguished and re-started frequently, as may be the case in motion picture projectors.

In Figs. 3 and 1, I have illustrated a modified arrangement of the invention previously described. With the controlling switch in the position shown in Fig. 1, and only the lamp 7 in operation, the generator is difierentially compounded, the series coil 2 opposing the shunt coil 3, thus producing the constant current efiect desired for the arc. When the handle 22 of the controlling switch is thrown to the left, and bothlamps are in operation, as illustrated in Fig. 4, the series coil 2 is short-circuited by a conductor 2 inserted between the plugs 12 and 17 on the switchboard, and the generator accordingly operates as an ordinary shunt wound machine. In this modified arrangement I prefer to employ an adjustable resistance 13 to regulate the shunt circuit.

It will be understood that the generator may be driven by an engine or by means of an electric motor of either the direct or alternating type. V

I have described in detail the particular arrangement illustrated in the accompanying drawings, for the purpose of disclosing an embodiment of my invention, but it will be obvious to engineers that various changes can be made therein within the scope of my claims and without departing from the spirit of my invention.

Having thus described my invention, I claim:

1. A system of electrical distribution for are lighting, comprising a generator having series and shunt field windings, a plurality of translating devices in circuit therewith, and means whereby the generator circuits may be connected to deliver a current of constant current output when supplying one translating device and a constant potential output when supplying a plurality of translating devices. 7 p

2. A system of electrical distribution for are lighting, comprising a generator having series and shunt field windings, a plurality of arc lamps in circuit therewith, and means for connecting said windings either in compound or differential relation and correspondingly connecting either a plurality of lamps or a single lamp in circuit.

3. A system of electrical distribution for are lighting, comprising a generator having series and shunt field windings, a plurality of arc lamps, and means for connecting said windings in opposition and one of said lamps in circuit with the generator and in compound relation with a plurality of said lamps in circuit with the generator.

4. A system of electrical distribution, comprising a generator having series and shunt field windings, a plurality of translating devices, a resistance element, and means for connecting said field windings in compound relation and different portions of said resistance in series respectively with separate translating devices and for connecting said field windings in opposition and different portions of said resistance in parallel with each other when operating only one of said translating devices and in series therewith.

5. A system of electrical distribution, comprising a generator having series and shunt field windings, a plurality of translating devices connected in parallel thereto, a resistance element, and means for connecting different portions of said resistance in series respectively with separate translating devices and said field windings in compound relation when said translating devices are operated simultaneously, and for connecting said resistance portions in parallel and in series with one translating device and said field windings in differential relation when operating only one of said translating devices.

6. A system of electrical distribution, comprising a generator having series and shunt field windings, a plurality of translating devices connected in parallel thereto, a resistance element, means for connecting different portions of said resistance in series respectively with separate translating devices and for causing the generator to deliver a current of constant potential output when a plurality of translating devices are simultaneously operated, and for connecting said resistance portions in parallel with each other and in series with the translating devices when operating only one of said translating devices.

7. A system of electrical distribution, comprising a generator having series and shunt field windings, a' plurality of translating devices connected in parallel thereto, a plurality of resistance devices, switching means and connections for placing the field windings in opposition, when the switching means is thrown into one position so that the current derived from the generator will be of constant current output and traverse one half of the resistance and through one translating device, and when the switching means is thrown into the opposite position the windings will be connected in compound relation so that the current will be of constant potential output and traverse two halves of the resistance in parallel and two of the translating devices.

In testimony whereof, I aflix my signature, in the presence of two witnesses.

JOSEF HENRIK HALLBERG.

Witnesses:

LESTER BEARDSLEY, HELEN E. KRELSCH.

Copies of thin patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

